1. Field of the Invention
As an alternative to using conventional straps to retain eyeglasses around the wearer's neck, the instant invention allows the temple piece or arm to rotate about its longitudinal axis so that the curved ends will rotate toward each other to reduce their spacing. When rotated in this manner the ear pieces can extend behind the wearer's neck to retain the glasses when not in use. This approach would be suitable for a user who cannot use his reading glasses for normal vision, or cannot use his normal glasses or even his bifocals for reading. It could also be used with sunglasses.
2. Description of the Prior Art
U.S. Pat. No. 5,229,795 does disclose an eyeglass frame in which the temple pieces can be folded into a flat configuration so that the glasses can hang flat against a wearer's neck. However, the temple pieces can only be folded in a direction opposite from the orientation that would permit the earpieces to engage the wearer's neck to retain the glasses when not in use. These glasses require the use of a strap to retain them around the wearer's neck.
U.S. Pat. No. 4,029,403 discloses eyeglasses in which the temple and nose pieces are free to rotate so as to fit the profile of the wearer. These eyeglasses employ a ball and socket connection. It would appear that the ball and socket joint would permit rotation of the temple or earpiece about the longitudinal axis of the temple piece. There is, however, no description of this possibility, nor is there anything to suggest that this ball and socket configuration could be employed to position the temple pieces so that they would grip the wearer's neck. There is no detent on anything to hold the temple pieces in position, so even if the ear pieces could be folded into the proper orientation, there would be nothing to prevent them from returning to their original position, allowing the glasses to slip from the wearer's neck. The split ball configuration shown in this patent might also be too expensive to manufacture for this type application. The shape of the rear earpieces does not appear suited for gripping the rear of the wearer's neck.
U.S. Pat. No. 3,476,466 discloses eyeglasses having a ball and socket hinge. This ball and socket can pivot about a vertical axis and a horizontal axis perpendicular to the temple or ear pieces so that the temple pieces can be folded over the front or rear of the lens. However, the ball and socket joint does not permit the temple pieces to be folded about a horizontal axis through the temple pieces because there will be no clearance for the ball stem. Therefore, the temple pieces cannot be folded so that the ear pieces can grip the wearer's neck for retaining the eyeglasses.
U.S. Pat. No. 5,745,952 discloses eyeglasses with a constrained ball and socket joint. A collar is positioned to resist torsional rotation along the longitudinal axis of the earpiece. Therefore the earpiece cannot be rotated to grip the back of the wearer's neck
U.S. Pat. No. 3,278,981 discloses a ball and socket hinge, but this hinge appears to be intended for use on a door or door jam. The ball has a threaded member secured to the ball, and apparently the threaded member is screwed into a door or similar article. There is no apparent suggestion that the threaded member should be attached to a temple or earpiece employed in an eyeglass frame.
US Patent Application Publication 2005/0270480 discloses another ball and socket hinge, but this hinge cannot be rotated as required for the invention under consideration.
U.S. Pat. No. 6,062,690 is an example of a retainer or strap that can be mounted on a pair of glasses.